Bluetooth is an emerging standard with peer-to-peer short-range wireless technology (a cable replacement technology). Bluetooth is considered as a secure short-range wireless network to intend to provide pervasive connectivity, especially between portable devices like mobile computers, mobile phones, and other nomadic devices. Bluetooth radios operate in the unlicensed ISM band at 2.4 GHz with a set of 79 hop carriers with 1 MHz spacing. A sophisticated transmission model is adopted in the Bluetooth specification to ensure protection from interference and security of data. A frequency hopping spread spectrum technology is applied at the channel level. A slotted channel model is utilized with nominal slot length of 625 μs. For full duplex transmission, the Time-Division Duplex (TDD) scheme is employed.
A collection of Bluetooth devices may be connected in an Ad Hoc fashion. The Bluetooth devices may connect to each other to form a network known as a piconet. A device in the piconet may be enabled to operate a master or a slave on a per connection basis. A master may be a device that initiates communication over a piconet channel, while a slave may be a device that responds to the master for the duration of the piconet connection. A master may control and determine aspects of activities in the piconet. The master and the slave may alternatively transmit packets via time slots.
A piconet channel may be represented by a pseudo-random hopping sequence hopping through 79 RF channels. The hopping sequence is unique for the piconet and is determined by the Bluetooth device address of the master. The channel is divided into time slots where each slot corresponds to an RF hop frequency. The RF hop frequency remains fixed for the duration of a packet. Consecutive hops correspond to different RF hop frequencies. The nominal hop rate is 1600 hops/s. With regard to channel linkup, information in piconet is encoded in packets. Each packet is transmitted on a different hop frequency. A packet normally covers a single slot, but may be extended to cover up to five slots.
Each data packet may be transmitted independently by modulating an electrical or electromagnetic (radio or optical) signal in accordance with the packet's contents and transmitting the signal via the relevant communications medium to a receiver. Boundaries between successive packets in a symbol stream may be defined in various ways, such as by providing a fixed pattern of symbols to identify the start or end of a packet. A device receiving a transmitted signal may establish synchronization with a received signal before decoding the information in the received signal to recover transmitted bit patterns. For a Bluetooth enabled device, packets of information may be exchanged between Bluetooth enabled devices using TDD with alternating transmissions, and the basic signal recovering process involves waveform demodulation, dc compensation, bit synchronization and bit detection. Waveform demodulation usually is implemented in a Bluetooth radio module and dc compensation may be implemented either in the Bluetooth radio module or in the Bluetooth baseband. Bit synchronization and detection may be implemented in the Bluetooth baseband. Bit synchronization may be a critical process for achieving correct bit detection. In Bluetooth specification, a synchronization code is embedded in each Bluetooth packet to assist receive timing synchronization process for each packet received by the recipient.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.